June 21 marks the start of summer for 2019 – and the longest day of the year. Called the summer solstice, this day is when the Northern Hemisphere is angled closest to the sun. For centuries, cultures have celebrated this day. In our modern times, it’s also a day to celebrate nuclear energy.
Why? The longest day of the year coincides with warmer weather, meaning we all need reliable electricity more than ever to last through the long, hot summer days. It’s hard to find a more reliable source of electricity than nuclear power.
One way to quantify reliability is to consider capacity factor, which is the measure of how often a power plant runs for a specific period of time. In other words, it shows how often a plant is running at its maximum output. The U.S. Energy Information Administration found that in 2018 nuclear plants had a capacity factor of 92.6 percent. That means, nuclear plants ran at full power nearly all of the time. That compares to a capacity factor of 57.6 percent for natural gas, 37.4 percent for wind and 26.1 percent for solar.
The reason nuclear plants achieve the highest metric of reliability is because they are designed for continuous operations – 24 hours a day, seven days a week for 18 to 24 months. Because of their reliability, nuclear power is considered a baseload power source: a resource that produces electricity nearly all the time.
In comparison, wind and solar are considered intermittent sources because they require the wind to blow or the sun to shine. There’s no doubt it takes a variety of energy sources to power our daily lives, but it’s critical to have a carbon-free, baseload power source like nuclear as the backbone of the electric grid.
At Duke Energy, our plants demonstrated this reliability in action. In 2018, McGuire and Oconee Nuclear Stations set generation records, the two units at our Catawba Nuclear Station operated continuously for more than 500 days, and our Brunswick, Harris and Robinson plants provided millions of megawatt-hours of electricity to our customers. For 2019, our plants are poised for similar reliability successes.
So, take a second on June 21 to consider when you turn on a light, charge your phone, or feel cool air from your air-conditioning, our six nuclear sites are operating around the clock so you have the electricity you need for the longest day of the year.